Thus, although there are only three isoforms expressed in human skeletal muscle, there are many more hybrid muscle fiber types comprising muscle fibers with
several different isoforms within the same muscle fiber (see review by Scott et al. 2001).
A few receptor genes have more than 8
different isoforms (38 VRs and 10 ORs), however in most of these cases this is due to the presence of
several transcription start sites (TSS) or exons that differ in length by just a few nucleotides, so
several of the final transcripts differ only very slightly (Figure S7B).